Frontier Heating Refrigeration and Air Conditioning Inc: http://registry.faa.gov/N8335ANTSB Identification: GAA16CA49214 CFR Part 91: General AviationAccident occurred Saturday, September 10, 2016 in Sidney, MTProbable Cause Approval Date: 04/04/2017Aircraft: CESSNA 170, registration: N8335AInjuries: 3 Uninjured.NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.The flight instructor reported that, during the instructional flight in a tailwheel-equipped airplane, the student pilot bounced the landing. The airplane bounced off the grass airstrip, and the flight instructor took the flight controls, but the airplane drifted to the left and into a drainage ditch. The flight instructor reported that he corrected with right rudder application to ease the airplane out of the ditch, but the left landing gear tire deflated, and the left wing and the tail struck the ground. The airplane yawed to the left, the instructor corrected the yaw, and the airplane rolled onto the runway and stopped. The left wing, left aileron, and the elevator sustained substantial damage.The flight instructor reported that there were no preaccident mechanical malfunctions or anomalies with the airplane that would have prevented normal operation.The National Transportation Safety Board determines the probable cause(s) of this accident as follows:The student pilot’s improper landing flare, which resulted in a bounced landing, and the flight instructor’s inability to recover the airplane, which resulted in a runway excursion.